My DD was very calm about the whole thing and we had not made it into a big deal - saying it would just give her more choices. We had visited our nearest Gram (SHS) and the local Comp (behind our house). DD really liked the comp (we did too) and knew most of her friends were going there so was not worried if she didn't pass. She was less enamoured of SHS. We said it would not matter where she went as she would be herself and do well.
All this changed when we went to the Pates open day because she really fell in love with it. She was striding around saying she belonged there. She went to pieces on her next practice because it all suddenly mattered to her. We reiterated our mantra about it not being so very vital and reminded her how she had liked the comp. She managed to regain her equilibrium within a few days.
On test day itself though she said that as soon as she entered the test room it suddenly seemed like the whole world depended on it, mostly due to the large number of intent girls I think.
We did not tell DD when the results were due. As far as she was concerned it was done with. So only DH and me had stress the following week and DD got happy surprises on Saturday morning. Her relief at the top 120 for Pates showed that she had been a lot more stressed than she showed.
DD knows I go on the forum and is amused by it. She reminds me that I critisise her for going too long on the computer when there are other more fun things to do